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Reliability of the 30-15 Intermittent Fitness Test in Semiprofessional Soccer Players

in International Journal of Sports Physiology and Performance
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The purpose of this investigation was to determine the reliability of the 30-15 Intermittent Fitness Test (30-15IFT) in semiprofessional soccer players.


Fourteen male semiprofessional soccer players performed the 30-15IFT on 2 occasions separated by 7 d. Reliability was assessed by intraclass correlation coefficient (ICC), typical error of measurement expressed as a coefficient of variation (CV), and smallest worthwhile change (SWC) to determine any significant difference between testing sessions.


Maximal intermittent running velocity (VIFT) demonstrated good reliability (ICC = .80) for between-sessions reliability. The CV was 2.5% for between-sessions reliability of the 30-15IFT. As the SWC (0.70 km/h) falls within the range in which the individual’s true score is likely to lie (1.0 km/h), the usefulness of the VIFT was rated as marginal. Despite the usefulness of the 30-15IFT being deemed marginal, a change in performance as small as 1.0 km/h (2 stages) in VIFT could be considered substantial or real.


This study demonstrates that VIFT in the 30-15IFT is reliable, resulting in a reliable assessment of team-sport-specific cardiorespiratory fitness, with changes as small as 1.0 km/h (2 stages) in VIFT considered meaningful.

The authors are with the Directorate of Sport, Exercise and Physiotherapy, University of Salford, Salford, UK.

Address author correspondence to Christopher Thomas at C.Thomas2@edu.salford.ac.uk.